Heretofore, a microscope apparatus capable of observing a sample while switching its observation between an epifluorescence observation and a TIRF (Total Internal Reflection Fluorescence) observation using evanescent light is known (for example, see Japanese Unexamined Patent Application, Publication No. 2003-279860, Japanese Unexamined Patent Application, Publication No. 2003-29153, and Japanese Unexamined Patent Application, Publication No. 2009-98229. Microscope apparatuses disclosed in JP 2003-279860 and JP 2003-29153 have a configuration in which illumination light is moved in a direction perpendicular to an optical axis of an objective lens by causing the illumination light to be refracted by a parallel plate, thereby enabling switching between the TIRF observation and the epifluorescence observation. The microscope apparatus disclosed in JP 2009-98229 has a configuration in which the position of an outlet end of an optical fiber that emits illumination light is switched and thereby the illumination light is moved in a direction perpendicular to an optical axis of an objective lens at the pupil position of the objective lens, thereby enabling switching between the TIRF observation and the epifluorescence observation.